Sonochemistry and Cavitation

by

Milia A. Margulis

All-Russian Research Institutefor Organic Synthesis Moscow, Russia

Translated from the Russian by Garson Leib

Gordon and Breach Publishers Australia • China • France • Germany • India • Japan • Luxembourg

Malaysia • The Netherlands • Russia • Singapore • Switzerland Thailand • United Kingdom • United States

CONTENTS

Preface xi

List of Symbols xvii

Chapter 1. Acoustic Cavitation in a Liquid 1

1.1. Basic Parameters of a Sound Field 1 1.2. Definition of Cavitation 4 1.3. Cavitation Types 6 1.4. Cavitation and Boiling of a Liquid 6 1.5. Model ofVapor-GasNucleus 9 1.6. Formation Kinetics and Stability of Bubbles 12 1.7. Distribution of Bubble Nuclei in a Liquid 15 1.8. Microbubble Stability in a Liquid 21 1.9. Causes of Micro-inhomogeneity Formation in a Liquid 23 1.10. ThresholdofDeveloped Cavitation 25 1.11. Dynamics of Onset of Developed Cavitation 30 1.12. Cavitation Processes at Low Ultrasound Intensities ^3 1.13. Harmonie Components of the Cavitation Noise 37 1.14. Optical Methods of Studying Cavitation 44 1.15. Deformations of Bubbles 51 1.16. Hydrodynamic Cavitation in a Liquid 60 1.17. Cavitation in Low-frequency Acoustic Fields 66 1.18. Physicochemical and Chemical Effects in Low-frequency

Fields 71 1.19. Change in Gas and Liquid Concentration Produced by

Ultrasonic Waves 82 1.20. Influence of Temperature and Pressure on Cavitation

Processes 86

VI Contents

Chapter 2. Theoretical Concepts of the Mechanism of Physical and Physicochemical Effect of Cavitation 89 2.1. On the Model of a Collapsing Bubble 89 2.2. Thermal Theories of Cavitation (General Approach) 91 2.3. Dynamics of Cavitation Bubble Pulsation and CoUapse 95 2.4. Bubble Pulsation with Consideration of Liquid

^ Compressibility 101 2.5. Conditions of Shock Wave Formation in Collapse of Cavitation

Bubbles 105 26. Compression of Cavitation Bubbles with Consideration of Heat

Exchange 107 2.7. Compression of Cavitation Bubbles with Consideration of Their

Nonspherical Nature and Nonideal State of Gas 115 2.8. Determination of Maximum Parameters Achieved in

Compression of a Cavitation Bubble 117 2.9. Early Electrical Theories of Cavitation 122 2.10. Electrokinetic Phenomena Associated with Cavitation. A New

Electrical Theory. 127

Chapter 3. Sonoluminescence and Sonochemical Reactions 139 3.1. Luminescence of Various Liquids in an Ultrasonic Field 139 3.2. Sonoluminescence in Polymers 142 3.3 Ultrasonic Luminescence in Melts of Metals 144 3.4. Phase of Sonoflash Emission 147 3.5. Electrical Effects in Cavitation Fields 156 3.6. Experimental Models of a Cavitation Bubble 161 3.7. Sonoluminescence Quenching Effect 166 3.8. Sonoluminescence Spectra 173 3.9. Basic Elementary Processes in a Cavitation Field 193 3.10. Influence of Gases on the Rate of Sonochemical Reactions 214 3.11. General Analysisof Experimental Results 216 3.12. Joint Effect of Two Frequencies of Acoustic Oscillations 221 3.13. Chemical Reactions in Acoustic Fields of Various Configurations 225 3.14. Cavitation Produced by Hydrodynamic Emitters 229 3.15. Sonochemical Reactions in Various Solvents 237

Contents VII

Chapter 4. Energetics of Sonochemical Reactions and Physicochemical Processes Caused by Cavitation 241 4.1. Sonochemical Efficiency 241 4.2. Sonochemical Yieldof Products (Energy Yield) 244 4.3. Initial Sonochemical Yields of Products of Ultrasonic Water

Decomposition 245 4.4. Relation between Sonochemical Reaction Rate and

Sonoluminescence Flux 248 4.5. Dependence of the Rate of Chemical and Physicochemical

Effects Produced by Cavitation on the Ultrasound Intensity 250 4.6. Sonoluminescence Energy Yield and Its Experimental

Determination 263 4.7. Experimental Methods of Sonochemistry 268 4.8. Experimental Determination of Efficiency of Acoustic

Emulsification 273 4.9. Solid Particle Dispersion in an Acoustic Field 275

Chapter 5. Kinetics of Sonochemical Reactions 281 5.1. Discussion of Cavitation Region Model 281 5.2. Steady State for Mean Radical Concentration 282 5.3. Change in the Averaged Concentration of Radicals during a

Period 284 5.4. Cavitation-Diffusion Theory of Radical Distribution in Space

and Time 287 5.5. Determination of the Radical Recombination Coefficient 298 5.6. Mathematical Modeling of Radical Reactions in a Cavitation

Bubble 301 5.7. Classification of Sonochemical Reactions 310

Chapter 6. Sonochemistry of Water and Aqueous Solutions 313 6.1. Features of Experimental Results 313 6.2. Sonolysis of Chloracetic Acid Solutions. Problem of Hydrated

Electron Formation 318 6.3. ReductionofCerium(IV) Sulfate 327 6.4. Oxidationoflron(II) Sulfate 330 6.5. Redox Processes in Solutions of Iron(III) Complexes 332

viii

6.6.

6.7. 6.8. 6.9.

6.10

Contents

Formation of Hydrogen Peroxide and Molecular Hydrogen in Water Sonolysis Sonolysis of Formates

Calculation of Initial Sonochemical Yields Sonochemical Reactions in Water and Aqueous Solutions in a Nitrogen Atmosphere

. Initiation of an Ultrasonic Chain Reaction of Stereoisomerization of Ethylene-1,2-dicarboxylic Acid and Its Esters

338 341 345

353

363

Chapter7. Oscillatory Reactions in an Acoustic Field 371 7.1. Effect of Ultrasound on the Belousov-Zhabotinskii Oscillatory

Reaction 372 7.2. Initiation of Oscillatory Reactions in a Solution of

Dichlorosilane Oligomers and Polymers 394

Chapter 8. Effect of Ultrasonic Waves on Chemical Reactions in Nonaqueous Systems 8.1. 8.2. 8.3. 8.4. 8.5. 8.6. 8.7. 8.8. 8.9. 8.10.

8.11. 8.12. 8.13. 8.14.

8.15. 8.16. 8.17. 8.18.

Pyrolysis of Hydrocarbons Oxidation of Hydrocarbons Oxidation of Aldehydes and Alcohols Decomposition and Dimerization of Alkyl Halides Reaction of Halogen Derivatives with Metals (Wurtz Reaction) Alkylation of Aromatic Compounds Preparation of Thioamides and Thiocarbamates Synthesis of Organometallic Compounds Selected Reactions of Metals Reaction of Alkyl Halides with Metals and Carbonyl Compounds (Barbier Reaction) Reaction of Alkyl Halides with Metals and Dimethylformamide The Ulimann Reaction Reduction by Hydrides on Metals Reactions with the Participation of Halide Acetates and Zinc (Reformatskii Reaction) Cycloaddition Reactions of Halide Derivation Exchange Preparation and Reaction of Perfluoroalkyl Compounds Carbene Synthesis

407 408 410 413 418 419 420 421 426 428

430 431 433 434

435 437 439 439 441

Contents ix

8.19. Dimerization and Oligomenzation of Silane and Stannane Halides 442

8.20. Dissociation of Metal Carbonyls and Ligand Substitution 443 8.21. SynthesisofNitriles 449 8.22. Preliminary Conclusion 450

Chapter 9. Catalytic and Electrochemical Processes in an Ultrasonic Field 455 9.1. Homogeneous Catalysis by Metal Carbonyls 456 9.2. Heterogeneous Catalysis by Metals 458 9.3. Electrochemical Processes 469

Chapter 10. Reactions of Macromolecules in an Ultrasonic Field 471 10.1. Destruction of Polymer Molecules 471 10.2. Formation of Block and Graft Polymers 479 10.3. Polymerization in an Ultrasonic Field 484

Chapter 11. Prospects of the Technological Application

of Ultrasound 489

References 497

Index 517 Appendix 525 A. 1. Chemical Reactions and Sonoluminescence in Pulsed

Ultrasound Fields 525 A.2. Evidence that Acoustically Excited Gas Bubbles Carry

a Negative Charge 530 A.3. A Holographie Study of Shock-Wave Formation in a

Cavitation Field 535 A.4. Some Investigations of Sonoluminescence by Single, Stable

Cavitation Bubble Techniques 536